U.S. Pat. No. 3,929,678 issued Dec. 30, 1975 discloses long-chain zwitterionic compounds and a method of preparing them.
Sharon G. Boots and Marvin R. Boots, J. of Pharm. Scien. 64. 1262 disclose a four-step synthesis of carnitine compounds represented by the formula ##STR1##
Sharon G. Boots and Marvin Boots (Ibid) p. 1949 disclose the method of synthesis of 4-dialkylamino-3 hydroxybutyric acid, hydrochloride analogs of carnitine, by treating tert-butyl 3,4-epoxybutyrate with an appropriate amine, or amino chloride in methanol followed by a mild hydrolysis.
Diehl, et al., U.S. Pat. No. 3,504,024, disclose phosphonio carboxylates prepared as follows: A suitable tertiary phosphine is reacted with .omega.-chloro or .omega.-bromo carboxylate and then the resulting mixture is saponified.
Copending applications of J. McGrady and Laughlin, Pharmaceutically Active Zwitterionic Surfactants, Ser. No. 960,974; J. L. Fu, Y. C. Fu, R. G. Laughlin, J. S. Widder, J. P. Brown, Zwitterionic Pharmaceutical Composition, Ser. No. 878,147 relate to zwitterionic compounds.
U.S. Pat. No. 3,822,344 discloses N-alkyl substituted derivatives of glycine or its homologues which can exist in the form of zwitterionics.
The hydroxyl-substituted zwitterionic compounds of the present invention are disclosed and claimed in the co-pending U.S. patent application of Degenhardt and Gosselink, Ser. No. 043,561, filed May 29, 1979.